Unshrinkable wool and woolen material



Jan. 1925- 1,522,555

s. R. TROTMAN UNSHRINKABLE WOOL AND WOOLEN MATERIAL Filed April 1923 IN VEN TOR JM Mm A TTORNE Y become less distinct and fibre in progressive and strength and Patented Jan. 13, 1925.

UNITED STAT nsHnINKaaLE wo oL AND wooLEN MA'rEn InL. I

Applicationfiled April is, 1923. sea-am. 632.568.

To aZZ whom it may] concern I Be it known thatfI, SAMUEL: TRo'rMAn, a su'byect of the King of England,

residing at Nottingham, England, have in-' vented certain new and/useful Improvements in Unshrinkable Wool and VVoolen Materials, and I dohereby declare'the fol-f lowing to be a full, clear, and exact description of the invention, such as will enable others skilled in the 'art to which it fappertains/to make and use the same. I

This invention relates tov the preparation of socalled unshrinkable wooland'woolen' to the cortical cells, the tensile strength materials.

Hitherto, chlorination of wool, i for the purpose-of making it unshrinkable, hasbeen 1 the;percentage of damaged vfibre and'prop unsatisfactory. Insufliciently treated material is unsatlsfactory because it is not sufliciently unshrinkable,.fand when present methods are carried far enough to render thematerial unshrinkable for ordinary pur-, poses, the wool losesmuch weight, loses tensile strength, soluble and contains a high percentage of damaged fibres. I;

It is theobject of this invention to provide an improved and woolen material shrinkable with a with substantial retention of the original properties of the wool. It

isthe further object of this-invention, to

provide such a processthatcan easily be controlled and that can be effectively operated on a large scale.

lVool fibre is composedot a cortex cov -Y ered with epithelial scales. In ordinary wool, the free edges of theepithelial scales are always distinctly visible. In chlorinated Wool, these edges 8116x110 longer visible but appearto adhere to the cortex. In properly chlorinated wool, the epithelia scales present a smooth, opaque surface with perfectly plain outlines. With progressive chlorination,- the outlines of these, scales appear. As the scales become.thinner,-the .cortex becomes visible.

by the disappearance of the epithelial. scales exposing the cortex of the fibre. :This gives. the fibre a rough surface marked with longn tudinalstreaks. @Damage of this character "or less of chlorine on the weight (of the.

; wool.

may be either local or general.

The accompanying drawings-show diagrammatic and enlarged 'portionsof wool stages of chlorination.

RUSSELL" fcipally less large numbers ofthe epithelial scales marked increase.

washing.

wears badly, becomes more.

process of rendering woolsubstantlally 1m; minlmum loss of weightv gradually they dis- Damage is denoted Y "the out- Figured illustrates the Emmett-d wool" fibre clearly showing" the free" edges ofthe epithelial'scales'. Figure 2 illustrates a'w ell chlorinated samplestill showing lines of'the epithelial scales. fPFigure' 3 il lustrates a further showing 'inclplent damage. Figure 4 illustrates excessive chlorination shOWingcOmplete destruction of the epithelial scales.

The tensile strength of the wool is prina function of the cortex and, un-

aregdamaged or unless damage proceeds is not materially afiected. Increased affinity stage or chlorination for dyes is approximately proportional 'to' erly chlorinated wool does not show any a break-down rapidly/in wearing and in show any marked increase" The epithelial scales are more resistant 1S increased. Such damage decreases the wear ability and washability of the wool 'and also causes undue loss in weight.

If the fibre is badly damaged, it wets immediately and becomes soft and almost slimy. Such damage causes Undamaged material, does not in,- aflinityj for moisture over the untreated material.

When wool is treated with solutions con tai'ning free chlorine, such as chlorine water,

v cess acid, the initial absorption is so ra id"-v or bleaching powder solutions containingexthat the reaction becomes uncontrolla lefl and the wool fibre is immediately damag'ed. Likewise whenthe wool is soured or subw'ool fibre is. damaged upon immersion in because the acid upon the ected to a preliminary acid dr'ench, the

tion, in excess of that .requ-iredto combine with the base.

Moreover, when wool is treated with: such" 1 solutions containing free chlor1ne,-sens1ble damage 15 produced with very low absorp tion of chlorine. .With such solutions, dam-.

age results even with anabsorption pt 1% I have found that v by subj acting: the "wool or woolen material to treatment with hypoa chlorousacid substantially free from chlorine, the wool or woolen material is rendered unshrinkable for all practical purposes without undue loss of weight or strength of the orig- Percentage of chlorine absorbed.

Time in minutes. Bleaching Hypupowder chlorous and hydro acid. chlorit acid.

Percentage of chlorine absorbed.

. Bleaching powder and hydrochloric acid.

Time in minutes.

ll 'pochloi'ous acid.

The rate of chlorine absorption from acidified bleaching powder solutions was approximately three times as great as that from a solution of hypochlorous acid substantially chlorine free. In each of these comparisons the concentration of available chlorine and the total available chlorine in the solutions compared was identical. Chlorine water actsin'the same manner the acidified solution of bleaching powder.

I have further found, that with hypochlorous acid, sensible damage is not produced in the wool until over 4% of ChlOIlDG' on the weight of the wool has been absorbed.

With anabsorption between 4% and 5%,

traces of damage are sometimes visible, but this damage is not serious when it does occur and 18 of a nature not unusual in the best class of goods which have been made 1111- 'terials to render them unshrinkable.

shrinkable. When free chlorine is present. however, absorption in amounts as low as 1% or less cause damage, as has been pointed out.

I have found that the slow reaction rate of hypochlorous acid combined with the comparatively high chlorine absorption possible without injury with this material makes hypochlorous acid peculiarly suitable for the treatment of wool and woolenma- The slow reaction rate renders it easy to control the reaction and the high chlorine absorption possible without injury, diminishes the effect of any variation in the time factor and materially cuts down spoilage. In the first of the examples just given, for instance, a dangerous amount of chlorine, over 1%, would have been absorbed in less than two minutes using the acidified bleaching powder solution, whereas, using a solution of hypochlorous acid, would have to elapse before a dangerous amount of chlorine was absorbed. In the second example, using the acidified bleaching powder solution a dangerous amount of chlorine would have been absorbed in less than two minutes, whereas, with a solution of hypochlorous acid over twenty minutes would have to elapse before a dangerous amount of chlorine was absorbed. Chlorine water acts in the same manner as acidified bleaching powder solutions.

I have further found, however, that it is not necessary touse as large a quantity of chlorine to produce unshrinkability as can. safely be used as hypochlorous acid. chlorine absorption of between 4 and is possible without damage from a solution of hypochlorous acid, but I have found that unshrinkability, for practical purposes, accompanied by absence of damage, is produced by chlorine absorptions as low as 0.25% to 0.5% from hypochlorous acid solutions. lVi'th such small quantities of chlorine as hypochlorous acid, say less than 1%, there is the further important advantage that time is not an important factor. Vool and woolen materials may be left in such solutions for a long time with impunity, in fact until all the hypochlorous acid is used up. Using hy i ochlorous acid in small percentages. there: is practically no loss of weight during the process beyond that due to water alone.

Low concentrations of hypochlorous acid do not give absolute unshrinkabilitiy but will produce a fabric unshrinliable for all ordinary purposes. Concentrations of 0.25

over thirty minutes follows: Boil "a piece of fabric of measured area, say six inches square, for' 'one hour in strong soap and water with occasional rub bing during this. period, then wash the fabricseveral times in clear hot. water, and remeasure after dryingit. Fabrics treated with such low percent-ages will show a slight shrinkage by this test. On the other hand.

. or damage to the fibres becomes appreciable.

available chlorine.

It will be apparent that the quantity used depends upon the result desired.

Using low chlorine absorptions, dilute solutions can be used withoutunnecessary increase in bulk, however, control of the solution concentration 'is a readily used means to control the process." Concentration control" may be operated separately from or in conjunction with the control of total The permissible time of immersion without a dangerous absorption of chlorine is shorter. the more concentrated the solution. I have found that sensible damage becomes apparent only when the concentration of chlorine as hypochlorous acid exceeds 3'grams per litre. Chlorine concentrations, as hypochlorous acid, of 2 grams per litre; or less will cause neither damage nor undue loss in weight.

Using even concentrated solutions and a high total chlorine content, the time required to cause commercial damage to the wool or woolen material treated with solu tions of hypochlorous a id substantially chlorine free is so long that'the process is practically fool-proof on a large scale. In

the or linary commercial'proccsses, the loss in weight and amount of damage is considerable and variable.

predicable.

The following specific example. will serve to more fully illustrate the practice'of my invention, but it is not intended as any limitation of the scopeof'the invention.-

To treat a woolen fabric, Ifind it preferable to first wet it with about twenty times its own weight of water." I then lift the fabric out of the bath and stir in a suflicient amount of a. solution of hypochlorous acid, substantially chlorine free, of known concentration, to obtain the necessary percentage of chlorine in the bath, say 0.5%. of the weight of the fabric. I find it preferable for ease of working to then dilute the bath to about thirty times the weight of the fabric although this is not essential. I then return the fabric to the bath and work c fTh'e results of the present process, on theother hand are readily c-asionally for a period between and 'nnn'utcs. I then rinse the fabric and treat with a suitable dechlorinating agent such as sulturous acld or bisulphite. Following 1 this, the fabric'm'ay be washed in the usual treatment.

way' and then' subjected to any ordinary The fabric so treated is un-,:"

shrinkable and'sufl'ers no damage 'or undue loss of weight.

In the preferred practice of this inven-= tiou'. the solution of hypochlo-rous acid should be substantially chlorine free. Such solutions can be readily prepared by passing chlorine gasinto water containing chalk in suspension or a carbonate in solution. Such a solution should be allowed to stand for sometimeand the avaliable chlorine then determined by titration or other suitable means. If solution containing calcium. carbonate in suspension is not to beusedv forthwith, it is preferable to keep it in contact withthe chalk. Or a suitable'solution can be vprepared by treatingbleaching' powder solutions with boric acid. 'With low concentrations of either bleaching powder or boric acid such solutions substantially' consist of hypochlorous acid. With any concentrations the ratio of hypochlorous acid to free chlorine is very high. If strong bleach solutions and an excess of boric acid.

are used, free chlorine is also produced.

For concentrations up to 3 grams of avail-. able chlorine per litre a -mixture of bleaching powder and boric acid is hypochlorous acid substantially chlorine free.

Solutions of bleaching powder, up centrations of about 4% of chlorine onthe to con-.

weight of'the fabric, can hensed without I causing more than slight damage, suchas is. notinfrequent in the. best class of unshrlnkable goods as previously prepared, if the proper precautions are taken to avoid free *1 chlorine. Solutions of this character can be' preparedjin several ways.- For exain'ple,a

clear solution of bleaching powder canbe.

made up, the available chlorine determined I as by titration, and then properly diluted to the requisiteconcentration of available.

chlorine. This solution can then be treated with justsufiicient hydrochloric or sulphuric acid to neutralize the alkalinity and liberate 1 the combined hypochlorous acid. .This quantity can be calculated or experimentally determined. In practice it is usually sufiicientto carefully stir in dilute-acid until the mixture is no longer alkaline to litmus. \Vcaker acids can be used with corresponding advantage for slight excesses are not as critical, and in the concentrations used for the chlorination of wool, an excess will produce hypochlorous acid substantially I free from free chlorine. Weak acids such as acetic acid or phosphoric acid are-suitable and boric acid is particularly advantageous as has been pointed out. Or this 'solution' of bleaching powder may be treated with a slight excess of sodium bicarbonate, sodium acid phosphate or the like, or. solutions of the same. The. present invention can be practiced in conjunction with any methodforprepar ing solutions of hypochlorous acid which are substantially free from chlorine. Solutions of hypochlorous acid which contain quantities of cholorine thatvare without efiiect on the fabric are substantially free from chlorine.

for the purpose of the present invention. Due to the safety andsimplicity of operation, I prefer to use'solutions of hypochlorous acid substantially free from chlorine, but it will be; apparent that, by restricting the relative amount of free chlorine present, as compared to the amount of hypochlorous acid, below the point at which material loss of weight and fibre damage begins, the

ing wool and woolen material substantially unshrinkable without undue loss of weight or strength or damage to the materialby treatment with solutions of hypochlorous acid which can be easily controlled and effectively practiced ona commercial scale. Having described my invention, Iclaim: 1. The process of rendering wool or woolen material unshrinkable, comprising subjecting said wool 01'' woolen material to treatment with a solution of hypochlorous acid substantially chlorine free.

2. The process of rendering Wool or.

woolen material unshrinkable, comprising subjecting said .wool or woolen mater al to treatment with a solution. of-hypochlorous acid substantially freeffrom chlorine and hydrochloric acid. Y

3. The process of rendering wool or woolen material unshrinkable, comprising subjecting, said wool or woolen material to treatment with a solution of hypochlorous acid substantially free from chlorine, said solution containing not more than ,3 gra'ms of available chlorine per litre. V

at. The process of rendering wool or woolen material unshrinkable, comprising subjecting said wool or woolen material to treatment with a solution of hypochlorous acid substantially chlorine free, said solu:

tion containing, not more than 1% of available chlorine on the weight of the wool or woolen material. I p H I p 5. The process of rendering wool or woolen material unshrinkable, comprising subjecting said wool or woolen material to treatment with a solutionof hypochloro'us acid substantially chlorine free, said 'solution containing not more than 5% of available chlorine on the weight of the wool or woolen material.

6. The process of rendering wool or woolen material unshrinkable, comprising subjecting said wool or woolen material to treatment with a'solution of hypochlorous acid substantially chlorine free, sald solution containing not more than 1% of available chlorine on the weight of the wool or woolen material and not more than 2 grams of available chlorine per litre.

7. The process of. renderingfwool or woolen material unshrinkable, comprising subjecting said wool or woolen material to treatment with a solution of hy ochlorous' containing about 0.5% of available chlorine on the weight of the wool or woolen material for a 45 1ninutes. j a 8. The process of rendering wool or woolen material unshrinkable, comprising subjecting said wool or woolen material to treatment with a solution containing hypochlorous acid and maintaining the concen- V tration of free chlorine below the point at acid substantially. vfree from ch crime and period of between about 30 and which loss of Weight and fibre damage be:

comes appreciable. j

9. The process of rendering wool or woolen material unshrinkable, comprising subjecting said wool or Woolen material to treatment with a solution of hypochlorous acid substantially free from chlorine and then subjecting. the wool or woolen material In testimony whereof I aflix my signature.

SAMUEL RussELi. TBOTMAN.

to treatment with a dechlorinating agent. 

